Do your research on your apps and plugs to see if updates are required for ML.
Chances are that SL doesn't have the drivers to support the new hardware, and you may,
or may not be able to boot from the time capsule backup.
When I got my MBP I
used migration assistant to move key apps and files from my old machine, but it requires
both machines.
It worked fine but I had to reauthorize all apps.
What I usually do when upgrading the OS, is to clone my system drive then upgrade
the OS for testing before I move to the new OS.
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G-Dub
Studio G-fx 15inch quad-core i7 Macbook Pro Logic913